Dual pump



Nov. 13, 1951 E. J. 'SENNINGER DUAL PUMP Filed March 27, 1946 4Sheets-.SheetA 1 Nov. 13, 1951 E. .1. SENNINGER 2,575,074

DUAL PUMP Filed March 27, 1946 4 Sheets-Shee't 2 Nov. 13, 1951 E. J.SENNINGER DUAL PUMP 4 Sheets-Sheet 4 Filed March 27, 1946 Patented Nov.`13, 1951 DUAL PUMP Earl Joseph Senninger,` Chicago, Ill., assignor toSanniyer Corporation, a corporation of Illinois Application March 27,1946, Serial No. 657,359

My. invention-relates to pumping devices for use in apparatus whereintwo-fluids are pumped concurrently, with specialreference to suchapparatus in which one fluid is of gaseous character and the other fluidis a liquid.

While the invention is applicable broadly to dual pumping tasks and isadvantageous in various apparatus for'spraying mixtures of liquids andgases, such as paint mixtures, the invention b being initially embodiedin an apparatus for burning liquid fuels. This initial embodiment willbe described for the purpose of the present disclosure, since such adescription will provide adequate guidance for applying the inventionwherever it may have utility. Y

Oneof the important objects of my inventio l to provide a dual pump inwhich one pumping mechanism acts on non-compressible iluid'and a secondpumping mechanism compresses a compressible fluid inA such manner thatthe heat of' oompression generated by the second pumping mechanismmay betransferred to the ilrstf-mentioned fluid for useful purposes. In thepresent embodiment of the invention that useful purpose is to pre-heatthe fuel oil prior to delivery of the fuel oil to the burner nozzle.

In the preferred practice of my invention the heat of compressiongenerated in the dual pump is employed to lighten the preheatlng burdenthat is imposed onan electrical heater in` the fuel oil line. l In amodified or alternate practice of my invention, however, the preheatingof the fuel oil is provided primarily by the heat of compressiongenerated in the dual pump, and the electrical heater on the fuel lineis employed only temporarily in an automatic manner at the beginning ofa period of operation.

With further reference to the construction of the dual pump, one of myobjects is to provide a structure that may be readily dismantled forinspection, servicing or repairing, with special reference to the oilpump. It is contemplated that the oil pump will be readily dismantledwithout disconnecting or opening any part of the oil line in the system,and that such dismantling will not only make the interior of the oilpump accessible but will also expose for inspection a seal that isplaced between the two pumps. This object is obtained by connecting theoil line on the air pump 'casing and by mounting the oil pump in aremovable manner on the side of the air pump casing, .with suitableintake and discharge pas- 'sages provided in the air pump casing for theoilv pump.l The seal between the two pumps is mounted at or near thejuncture of the oil pump with the air pump casing. g K

Certain objects of my invention relate to the construction of the sealbetween the two pumps, it being my purpose to provide an e'ective seal 2chamber wall. In this regard a feature of the invention is theemployment of rings oi rubber, or the like, embracing the actuatingshaft, which rings are circular in cross-section so that in re, sponseto fluid pressure in one direction longitudinally of the shaft the ringswill tend to roll along the shaft into desired sealing positions.

Other objects of my invention relate to the construction of the air pumpper se. It iscontemplated that the air pump will be of a suitablechambered construction .whereby the oil may ,ow through the air pumpstructure for receiving heat generated by the air pump. In my preferredconstruction the casing i'or the air pump is constructed in the mannerof a Jacket to provide heat exchange chambers for the iiowing oil. Thusthe air pump by generating heat of compression supplies heat for raisingthe temperature of the oil and, conversely, the oil owing through thejacketed casing of the air pump serves as a cooling medium to preventoverheating of the air PllmlL A group of objects of my inventionrelating to the oil pump, per se, includes the following: To provide anovel arrangement in which two piston members aiord four piston heads tominimize the pulsations in the oil system; to provide` a novelarrangement of two piston members in which two pairs of piston heads areinterconnected, respectively, by two offset webs, with the webs inoverlapping. sliding relation for certain advantages; to provide anoverlappingrelationship between the two piston members whereby theamount of now or displacement movement by the four piston heads may begoverned by a single eccentric control; to provide what may be termed idove-tailed relationships in the configuration of the four piston headsthereby to increase the freedom of the piston heads for inward movementrelative to each vother for the purposeof achieving a relatively widerange of volume adiustment in a small compact oil pump; .and to provide,in such a construction, an eccentric control that is movable not onlythrough a range of eccentric positions but also to a concentric positionwheredrawings.

In the accompanying drawings, whichare to be regarded as merelyillustrative:

Fig. 1 is a diagram of the system with 'parts displaced in such a way asto reveal an organic whole in one figure;

where an actuating shaft extends through a oo Fig. 2 is a longitudinalsectional view of the preferred form of my dual pump taken on the line2-2 of Fig. 3;

Fig. 3 is a transverse section taken along the line 3-3 of Fig. 2. withcertain walls broken awa Fixg. 4 is a diagrammatic view indicating thestages by which the ltemperature of a liquid is raised in a preferredpractice of my invention;

Fig.- 5 is a transverse section taken as indicated by the line 5-5 ofFig. 2;

Fig. 6 is an elevation of two cooperating piston members employed in aliquid pump;

Fig. 7 is a section taken as indicated by the line 1-1 in Fig. 6;

Fig. 8 is a transverse section taken along the line 3-3 of Fig. 2;

Fig. 9 is a transverse section taken along the line 3-9 of Fig. 2; and

Fig. 10 is a portion of a wiring diagram to indicate a modified practiceof the invention.

General description In the diagram shown in Fig. 1 the main housing I8provides a tank or reservoir I I for lubricating oil, a chamber I2 forprimary or atomizing In the diagram in Fig. 1 a number of partsV thatare actually in the chamber I2 are, for the purpose of description,shown displaced downward and to the left. Among these displaced partsare a primary air supply line or tube I1, a nozzle I8, an oil supplyline I9, a heater associated with the oil supply line I9, and a pair ofelectrodes 2| associated with the nozzle for igniting the mixture of oiland air in starting the burner. The main housing I8 serves as a supportfor an electric motor 22 which drives a secondary air fan or blower 23,an air pump 24 for supplying primary air to the nozzle, and an oil pump25 for supplying fuel oil to the nozzle, these three driven devicesbeing shown spaced apart on the same axis.

As will be discussed in detail later the present invention is directedprimarily to the combined construction of the air pump 24 and the oilpump 25.

The secondary air fan or blower 23 takes air through the slotted sidewall 26 of the fan casing I5 under control of a rotary shutter 21 anddelivers the air through the draft tube I6 around the mixture of oil andair discharged from the orice 28 of the nozzle I8. The volume is variedby adjusting the rotary shutter 21.

The primary or atomizing air pump 24 takes air in through aperturesl29and delivers it through a pipe 39 into the upper portion of the mainhousing through the filter I3. The lubricating oil tank II is connectednear the bottom by a pipe 33 with the primary air pump 24, and by reasonof the air pressure within the chamber I2 oil from the supply 3I in thetank'l I is continuously delivered to the air pump. As a result thispump delivers a mixture of air and oil, or air and oil foam. to the pipewhereby the bronze wool in the lter I3 is made to serve as a combinedoil separator and air cleaner and the lubricating oil collected theredrops down over the outside of the draft tube I8 to return to the tankII. The lter I3 is separated from the filter I4 by a partition 34, andthe air compressed in the chamber I2 passes up through a second mass ofbronze wool in the iilter I4 before entering' the pipe 32.

In practice the apparatus is so designed that a normal pressure of fromfive to thirty pounds. for example, may be built up and maintained inthe chamber I2. The pressure in the primary or atomizing air system isregulated by ahy-pass 35 connected across the inlet and outlet of thepump 24 and controlled by an adjustable valve 36. In this diagram theby-pass is shown as external piping, butin practice may be incorporatedin the body or casing of the pump. if desired. I

Oil for fuel ,is stored in a suitablefuel supply tank (not shown) and isled from the supply tank through a pipe 33 to the oilvpump 25. Fig. 1shows the pipe 38 entering the air pump 24 instead of the oil pump 25,but, as will be explained in more detail later, concealed passages inthe air pump 24 lead to the intake of the oil pump 2l and other,concealed passages lead from the delivery side of the oil pump throughthe structure of the air pump to the oil supply pipe 39.

Where gravity feed cannot be used, an auxiliary pumpingequipment 31should be provided to boost oil from the supply tank to the oil pump.

The oil pump 25 delivers the fuel oil through the supply pipe 39 and thepreviously mentioned pipey I9 to a three-way valve that is concealed inthe nozzle I8. The three-way valve is governed by a pressure-responsiveactuator or automatic valve control 4I. At the idle or nonoperatingposition of the .three-way valve the end of the oil supply pipe I9 atthe nozzle I3 is placed in communication with a by-pass pipe 42 thatleads from the nozzle I8 back to the fuel oil supply tank. In responseto rise in pressure in the air supply pipe 32 the automatic control 4Imoves the three-way valve to its normal operating position, thereby toplace the end of the oil supply pipe I9 at the nozzle I8 incommunication with the nozzle orice 28.

The preferred construction of the automatic control 4I and the three-wayvalve and the nozzle I8, together with other associated parts in thedraft tube I6, is disclosed in detail in my copending application SerialNo. 657,358 now Patent 2,489,823 dated November 29, 1949, entitledLiquid Fuel Burner System, iild concurrently herewith.

When operation of the described arrangement is started, oil dischargedfrom the pump 25 through the supply pipes 39 and I9 is initiallyby-passed at the nozzle back to the supply tank through the by-pass pipe42. As soon as suiilcient pressure is built up in the fluid courseincluding the air chamber I2 and the air supply pipes 30 and 32 toinsure proper delivery of primary or atomizing air to the nozzle I8, thepressure-responsive actuator 4I will react to the rise in air pressureby operating the three-way valve in the nozzle I8 to cut off the by-passpipe 42 and to open communication to the nozzle orifice I8,

whereupon a fuel mixture of .oil and air is discharged in spray formfrom the nozzle for combustion. When for any reason the air pressure inthe chamber I2 drops below that for which the device is designed andadjusted, the pressure-responsive actuator 4I will operate the three-wayvalve in the nozzle to cut off oil flow to the nozzle oriiice 28 and tocause the oil discharged by the pump 25 to be returned to the supplytank through the by-pass pipe 42.

Any one of the many types of oil burner controis may be used with thissystem and none will be described in the, interest of brevity. It willbe sufficient to refer to Oil Heating Hand Book" by Hans Kunitz, secondedition, and The Starbuck Oil Burner Manual, 1941.

Electric powerfor the liquid fuel burner system described may be takenfrom the house line 45, and the apparatus shown in the diagram willbe.understood from the following description of the operation.

When the room thermostat or boiler control 4B calls for heat,Minneapolis-Honeywell R117 relay 41 will be energized and close anelectric circuit to the oil heater 20 and the ignition transformer 4l.After a delay period, for example twentyfive seconds. switch 48 willclose the circuit to motor 22, which will start the secondary air fan orblower 23, the primary or atomizing air pump 24, and the oil pump 25.While the pump 24 is building up the necessary pressure in the chamberI2, oil from the pump 25 is recirculated through the by-pass pipe 42 andthe heater 20 is conditioning the oil in the pipe I9 and warming up theassociated parts of the burner. When the pressure in chamber I2 reachesthe selected amount the pressure-responsive actuator 4I will operate thethree-way valve in the nozzle to cut of! the by-pass pipe 42 and permitmixed oil and air to be discharged through the nozzle orifice 2B. As themixture of air and atomized heated oil is discharged from the orifice 28of the nozzle sparks from the electrodes 2i ignite it, and the iiame isfurther fed by the supply of secondary air delivered by the fan orblower 23 through the draft tube I6. After a short interval, relay d1will shut off the current to the ignition transformer 49. The resistanceof the heater element it increases with the rise in temperature and thewattage drops to the selected limit' for the particular design.

Mention of Minneapolis-Honeywell R117 relay is merely by way of example.Many other controls can be used, and-some other controls must be usedwhen the fire adjusting apparatus, later described. is associated withthe burner.

Modulating the fire The operation of the apparatus described ispreferably modified by means to increase the fire after it is startedand then to modulate the fire according to the demand for heat. Oneembodiment of means to that end includes an air motor comprising acylinder 50, equipped with a piston 5I whose piston rod 52 runs througha guide 53 and has one arm 54 connected by a link 55 with the rotatingshutter 21 of 'the secondary air fan or blower, and another arm 56connected by a link 51 with a lever 58 on the oil pump 25 by which thecapacity of the oil pump may be adjusted and enlarged as the shutter 21is opened to increase the delivery of secondary air by the fan or blower23.

The piston 5| is normally urged to the position shown by a spring 59,and its limit in that direction is determined by a low re stop 60, itslimit in the other direction being determined by a high fire stop 6I,both adjustable on the piston rod 52 and made fast by set-screws or thelike.

In order to move the piston against the resistance of spring 59, airfrom the chamber I2 is conducted by a pipe 62 and delivered to a head Ichamber 63 in the air end of the cylinder 50 from which chamber the airpasses by a port 64 into the cylinder and exerts its pressure againstthe piston 5I. The length of the pipe 62 and the ad- Justment of aneedle valve will make the dow of air involve the time interval desiredfor response to change in demand, and the supply of air and oil will beincreased or decreased in relation to the pressure permitted to build upagainst the piston head, this function, however, being limited by theadjustment of low re stop 60 and high fire stop 6I. In some designs thelength of the pipe 62 will have a negligible eifect and the control willbe eiected chiefly by adjusting the needle valve 55.

With this arrangement the burner will start with a very small flame andgradually build up to the required size, as determined by the design andadjustment, and will stay there until the burner is stopped, at whichtime the spring will force the piston to low fire position. During themovement to low fire position the air in the cylinder will escapethrough the orifice 66 and the check. valve 61 back to the chamber I2and be discharged through the nozzle. Y

It is preferable, however, to add a, modulating control, one embodimentof which includes a pneumatic temperature or pressure device 68connected with the cylinder 50 by a pipe 69. When the temperature orpressure of the device 68, or the space to which it is subject, reachesthe point at which it is set, the arm 1I of the device 58 will uncoveran orifice 10 in the pipe 69. allowing some air to escape, thus loweringthe pressure in the cylinder 50 and allowing the piston to move towardthe air end of the cylinder under the action of the spring 59. reducingthe supply of secondary air and oil. The piston will adjust itself tosome point between high fire and low fire positions, depending on thedemand indicated by the arm 1 i. If the temperature or pressure at thedevice 68 should drop or increase, the port 1i) will be opened or closedcorrespondingly, and hence the re will be adjusted to correspond withthe demand.

It will lbe noted in Fig. 1 that the pipe 52 is connected to the headchamber 53 immediately above the check valve 51 and well below the port64 and the needle valve 65 associated therewith. The `advantage of thisparticular. arrangement is that any oil or foreign particles carriedinto the head chamber 63 through the orice 66 will be carried directlyinto the pipe 52, not into the region of the needle valve 65, so thatthere will be no tendency for the needle valve 65 or the port 64 to beclogged by such reverse iiow.

The device 68 may be any pneumatic control that will open a port on anincrease of temperature or pressure to bleed the air from the line 69 tothe atmosphere, or close the port on a decrease of temperature ofpressure, such. for example, as Minneapolis-Honeywell L-O92D. Thesedevices are available in a number of scale ranges and may be used as awarm air control mounted in the air stream, or as an immersion aquastatinserted in the liquid to be controlled, or as a steam pressure controlmounted in the boiler water just below the water line. The boiler watertemperature changes with the steam pressure in accordance with familiarsteam tables. As these devices and their applications are familiar,specific disclosure is omitted in the interest of brevity.

General arrangement for preheatz'ng fuel oil It is essential that thefuel oil supplied to the burner nozzle be preheated, and a feature of mydual pump construction is that one pump mechanism therein functions tocompress the air re- 7 quired for the spray action at the nozzle whilethe other pumping mechanism functions to pump the fuel oil to thenozzle-the arrangement being such that the heat of compressiongeneratedin the air pump mechanism is transferred to the liquid handledby the fuel pump. It will be apparent to those skilled in the art thatthe necessaryl heat transferring relationship between the twof pumpingmechanisms may be achieved by many different constructions. Therelationships involved in the preferred practice of my invention,however, are indicated diagrammatically in Fig. 4.

Fig. 4 shows diagrammatically the air pump 24, in whichheat ofcompression is continuously generated during normal operation of theapparatus. 'I'he previously mentioned pipe 38 for carrying oil from thesupply tank to the pump 25 communicates with what may be termed aheat-transfer or heat exchange chamber 80 or jacket chamber incorporatedin the casing of the air pump 24. From the heat-transfer chamber 80 theoil is conducted to the intake side of the oil pump 25, and on thedelivery side of the oil pump is discharged into a second heattransferor heat exchange chamber or jacket chamber 8| incorporated in theconstruction of the air pump 24. From the second heat-transfer chamber8| the previously mentioned pipe 38 leads to the fuel burner nozzle I8,but before the flowing oil reaches the nozzle it passes through thepreviously mentioned heating coil 20.

It is apparent that the described arrangement employed in the preferredpractice of my invention provides for raising the temperature of thefuel oil in four stages. the first stage of temperature rise being inthe heat-transfer chamber 80; the second stage being in the oil pumpitself,

Where the work done on the oil has a tempera-- ture increasing effectarising from friction among the oil particles; the third stage being inthe heat-transfer chamber 8|, and the flnal stage being provided by theheater'20.

Air pump construction motor 22, extends through both the end cap 83 yand the connecting body 85.

The shell 82 of the air pump has an inner cylindrical wall 81 eccentricto the shaft 86, and said shell also forms an upper filter chamber 88containing a mass of bronze wool 80. The sh'ell 82 of the air pump alsoforms two previously mentioned heat-transfer chambers 80 and 8|, the twochambers being on opposite sides of the air pump and being separated attheir lower ends by an inner wall 9|. As best shown in Fig. 3, theheat-transfer chamber 80 h s an intake port connected to the previouslym ntioned oil pipe 38 and an outflow bore 88 (Fig. 3) to the connectingbody 85. In like manner the other heattransfer chamber 8| has a deliveryport connected to the previously mentioned pipe 38 and an inflow bore 84(Figs. 2 and 3) to the connecting body 85. If desired, the oil line 38may be connected to the lower threaded opening 84 in the heat-transferchamber 80 for better oil circulation through the chamber 80, but testsindicate that such a change is not necessary.

'Ihe filter chamber 88 is covered by a removable cap 82 or closure thatis releasably held in place by a cap screw 83 threaded into a boss 88.Air taken in by the pump 24 enters the filter chamber 88 through thepreviously mentioned apertures 28 in the' filter chamber cap 82 andleaves the filter chamber through two recesses 81 shown in dotted linesin lFig. 3. Therais one such recess 81 on each side of the boss 85 inthe filter chamber, and each of these recesses communicates with anintake bore 88 leading to the corresponding end face ofthe casing shell.Near the` two intake bores 88 is a single parallel discharge bore |00that extends from end face to end face of the casing shell 82, whichbore communicates with a 'single bore or passage |0| leading to thepreviously mentioned pipe 30 for delivering compressed air from the pumpto the previously mentioned chamber |2. A suitable check valve |04 isincorporated in the passage |0| to prevent reverse flow of air from thepipe 30 to the pump.

Mounted on the shaft 86 inside the chamber formed by the cylindricalwall 81 of the pump is a suitable rotor |02, the rotor being eccentricto the cylindrical wall and in sealing proximity to the upper portion ofthe wall, as best shown in Fig. 3. Slidingly mounted in suitable radialslots |03 vin the rotor |02 are suitable pump blades |05, which bladesare thrown outward by centrifugal force and therefore tend to followclosely the cylindrical wall 81. Preferably the pump blades |05areiformed with suitable grooves |06 on their leading faces.

The end cap 83, which carries a suitable bear.'- ing |01 for the shaft86. is mounted on the shell 82 by suitable screws |08, together with lsealing gasket, and has suitable grooves on its inner face forming acurved intake passage i0 and a curved discharge (Fig. 9). The curvedintake passage ||0 communicates at its upper end with the correspondingpreviously mentioned bore intake 88, and the curved discharge passagecommunicates at its upper end with the corresponding discharge bore |00.As best shown in Figs. 2 and 9, the end cap 83 has formed therein asuitable passage ||2 which communicates with a passage ||3 in the pumpshell 82 whereby lubricating oil from the previously mentionedlubricating oil pipe 83 may reach the interior of the air pump.

A suitable bushing ||5, carrying a packing ring ||6 for the shaft 88, isthreaded onto a tubular extension ||1 of the end cap 83 to formtherewith a suitable chamber ||8 to serve as an oil sump on the outerside of the bearing |01. Lubricating oil under pressure is continuallyurged outward along the shaft'l through the bearing |01 for lubricationof the bearing and the excess oil tends to accumulate in the sump II8.To prevent excessive accumulation of oil in the sump ||8, the end cap 83has formed therein a suitable passage |20, shown in dottedlines in Fig.9, which passage leads from the oil sump to the intake zone of the airpump. In the construction shown, the passage |20 ends in the curvedintake passage I I0.

The connecting body 85, which carries a suitable bearing 2| for theshaft 86, is mounted on the pump shell 82 by suitable screws inserted inholes |22 (Fig. 5) together with a suitable gasket, and, like the endcap 83, has formed on its inner face a curved intake passage ||0 incommunication with one of the previously mentioned intake bores 88 and acurved discharge passage lll in communication with the previouslymentioned discharge bore |00. The connecting body 85 also has a suitablepassage |23, similar to the previously mentioned passage H2 (shown indot-l ted lines in Fig. 2), for conducting lubricating oil from the pipe33 to the interior of the pump.

One of the features of the present construction is a novel seal housedby the connecting body 85 for the dual purpose of preventing air leakagefrom the air pump 24 and of cutting off fluid communication along theshaft 86 between the air pump and the oil pump 25. As shown in Fig. 2, asuitable metal ring |25 is mounted on the outer face of the connectingbody 85 by suitable screws V|26, the metal ring being mounted on theconnecting body in a fluid-tight manner to serve in effect as part of achamber wall through which fluid flow is to be prevented.

Surrounding the shaft 86 adjacent the metal ring |25 is a sleeve 21having a cylindrical wall |28 spaced substantially from the periphery ofthe shaft and having a radial end wall |30 extending inward therefromtoward the shaft in abutment with the ring |25. The sleeve 21 is freelyslidable longitudinally of the shaft 86 but is engaged with the shaft torotate therewith. The required interengagement may be provided by a wirering |3| embracing the sleeve |21, the `wire ring having an endextending radially inward, as indicated at 32, to engage a short keyway833 in the shaft. Suitable means to continually urge the sleeve H21against the stationary ring 25 may comprise a circumferential series ofhelical springs |35 seated in a ring |36 that rotates with the shaft 55,the ring l35 being hacked against a shoulderl |31 on the shaft.Preferably the ring |25 is of relatively soft material, auch as bronze,while the sleeve |21 is of' harder material, such as steel. Such acombination of materials results in an effective fluid seal by the twocontacting relatively rotating faces.

To prevent fluid leakage inside the sleeve |21 at least one packing ring|38, and preferably two such packing rings as shown, are mounted on theshaft 86 inside the sleeve. Each of these packing rings |38 is made ofrubber, or similar elastic material, and is of circular cross-section,as shown, so that each ring tends to travel along the shaft by arollingr action in response to fluid pressure longitudinally of theshaft. In this in- Stance the prevailing pressure is outward from theair pump 24, so that the two packing rings |35 are urged toward theradial end wall |30 of y the sleeve 21. It is contemplated that the twopacking rings |38 will form an effective seal around the shaft becauseof their tight fit against the shaft and their contact with the sleeve|21. Preferably both of the rings have an unrestrained outside diameterslightly greater than the inside diameter of the sleevel |21, so thatthe rings are compressed in a fluid-tight manner by the circumferentialwall |28 of the sleeve. In addition, the pressure contact of one of the.packing rings |38 against the end wall |30 of the sleeve lprovides `afluid seal.

The connecting body 85 serves the various functions nf a casing memberor end cap for the air pump 24, a casingV member or end cap for the oilpump 25, means for mounting the oil pump on the air pump, and .finallyas means for communication between the oil pump and the previouslymentioned heat exchange chambers 80 and 8| in the air pump. For thelatter purpose the connecting body 85 has a peripheral enlargement |42(Fig. 5), to accommodate an inclined intake passage (not shown) `forcommunication between the oil pump 25 and the heat exchange chamber 80,this passage registering with the previously `mentioned outflow bore 89in the air pump shell. 'I'he connecting body 85 also has a secondenlargement |40 for a similar passage |4| (Fig. 2) for communicationbetween the oil pump and the other heat exchange chamber 8|, thissimilar passage communicating with the previ- `ously mentioned inflowbore 84 .in the air pump shell.

The operation of the air pump may be clearly understood from theforegoing dtscription. The valve 36 in the by-pass 35, showndiagrammatically in Fig. 1, is adjusted to maintain some selected normalpressure in the chamber I2 of the main housing, which pressure, forexample, may be within the range of iive to thirty pounds.

A feature of the present form of the invention, however, is that themoving parts of the primary air pump 24 are dimensioned with suchliberal clearances that plentiful lubrication of the pump interior isrequired to cause and maintain the selected normal pressure. By makingthe presence of a considerable amount of lubricating oil in the primaryair pump 24 necessary to seal it and to give it the required capacity,it becomes impossible to run the pump long with insumcient lubrication,for as soon as the pressure in the chamber I2 drops below that requiredthe supply of lubricating oil provided through the pipe 33 is cut offand a control of any one of the customary forms will put the apparatuson safety and shut the burner down entirely. If internal lubrication ofthe pump is non-existent, or is insuiiicient to adequately seal theclearance spaces, the pump will function at a lower level of efllciency,the pressure in the chamber i2 then being 'wo low for the valve control4I to maintain fuel oil flow to the nozzle but high enough to forcelubricant through pipe 33 to the air pump.

The required liberal clearance may be provided between any of variouscooperating surfaces. Thus the clearance may be at the side edges of theblades |05 or between the faces of the rotor and the end cap 83 and theconnecting body 85, or between the faces of the blades and thecorresponding faces and walls of the slots |03 in the rotor. Theprovision of such clearance requires only the ordinary skill expected inthis art, especially since the pressure created\by the pump runningwithout lubricant is not critical. For example, suppose the valvecontrol 4| is so adjusted as to cut oil? uid flow to the nozzle wheneverthe air pressure drops to five pounds. A minimum pressure of only onepound will lift lubricating oil through the pipe 33 to the air pump 24.Thus the clearance in the working parts of the air pump may be such as,in the absence of lubricant, to drop the pressure of the air pump to anyvalue between one and iive pounds.

Oil pump construction The oil pump 25 has a casing comprising a body orshell |45 and an outer end cap |46, the previ ously mentioned connectingbody 85 serving as a second end cap for the casing. Suitable long screws|41 serve not only for removably mounting the oil pump on the air pump,but also to interconnect in a fluid-tight manner the shell |45 of theoil pump casing and the end cap |46. Suitable gaskets make theconnections air tight.

The body |45 of the oil pump has a cylindrical liner |50 defining a pumpchamber and in which is mounted a suitable shaft or rotor |5|`, theline!l having an intake port |53 (Fig. 5) and a discharge aand/4 port|52. 'Ihese two ports |52 and |53 are in the form of extensive slots.The intake port |53 in the liner communicates withA an intake passagecomprising a radial bore |51 and a longitudinal bore |58, thelongitudinal bore |58 communicating with the previously mentioned intakena ssage (not shown) in the peripheral enlargement |42 in the connectingbody 85. In like manner the discharge port |55 in the liner |50communicates with a dischargeor delivery passage comprising a radialbore |55 and a longitudinal bore |56 (Fig. 5), the longitudinal borecommunicating with the previously mentioned delivery passage |4| throughthe connecting body 85 to the heat exchange chamber 8| in the air pump24.

The rotor |5| is operatively connected with the shaft 86 in any suitablemanner that will permit the oil pump to be readily disconnected from theair pump. In the present construction the operative connection isprovided by a small shaft Acoupler |60, having one tongue |6| extendinginto a slot |62 in the rotor and having a second tongue perpendicular tothe first tongue, the second tongue extending into a diametrical slot inthe end of the shaft 86.

The rotor |5| has a circular axial opening |65 from one end. and twodiametrical bores 180 apart intersecting the axial opening |65, thusforming four pump cylinders |66 90 apart. The axes of the twodiametrical bores are slightlv ofiset axially of the rotor. S'idinglvmounted in each of the two diametrical bores in the rotor is a pistonmember that preferablv is formed by cutting away the material of acylindrical block in such manner as to provide two coaxial piston headsintegrally interconnected by a suitable web. Thus. as bast shown inFigs. 6 and 7. there are provided two coaxial piston heads |61interconnected by an offset web |68. and a second pair of coaxial pistonhea ds |10 interconnected by a second oilset web I1 the operation of theapparatus.

It will be noted that the web |68 has a flat inner face |12 and the web|1| has a flat inner face |13, while the sides of each piston memberadiacent its web has flat faces |15 of angular configuration. Preferablythe recess in each cvlindrical block that forms the flat face of theinterconnecting web is somewhat shorter than the recesses that form thesides of the web, so that in the finished construction each of the fourpiston heads |61 and |10 has a corner notch into which either one of theadjacent piston heads may dove-tail or nest, as indicated in Fig. 6. Inpractice the pistons do not actually come into such mutual nest. ingcontact but do approach such contact, the dove-tail relationship and therelative narrowness of the piston webs thus permitting relativelyextensive inward movement of the pistons relative to each other therebyaffording exceptional range of radial piston movement.

When the two piston members are positioned with the corresponding pistonwebs |68 and |1| offset in the same direction, with the two webs insliding contact with each other, the four piston heads |61 and |10 willform a rectangular pocket |16, as best shown in Fig. 5. It is possiblefor the four piston heads to form such a pocket because they all cutsome radial planes of the rotor in common with each other. The pocket|16 may be termed a yielding pocket s'nce the four piston heads are freeto move radially.'

Extending into the pocket |16 is a circular means |11 that is of adiameter to occupy substantially to full cross dimension of the pocketand in normal operation is positioned eccentrically of the rotor |5| tocause pumping action of the four pistons in a manner well known in theart. The circular means |11 may be aptly termed a volume controleccentric for the oil pump, the adjustment of which determines the rateof positive displacement by the pump to supply fuel oil to the nozzleI8.

One of the features of the present construction is that the eccentriccontrol |11 is movable not only through a progressive range of eccentricpositions but is also movable to a concentric position at which the oilpump will not pump any oil to the nozzle I8. By virtue of such a,construction the eccentric control |11 may be manipulated in the samemanner as a valve, since it may be moved to a closed or no flow"position while the pump is operating, and may also be moved through arange of open" positions for different rates of oil flow.

Any suitable means may be employed to govern the position of theeccentric control |11 during In the present construction the eccentriccontrol |11 is in the form of a cylindrical body with a diametrical slot|18 in its outer end, the cylindrical body being mounted in a movablebase in the form of a metal block or disk |80. The disk |80, which has adiametrical guide slot |8| perpendicular to the previously mentionedslot |18, is movably mounted in a relatively large circular chamber |02formed in the oil pump body |45, and is guided by a pair of suitablepins |83 that extend from the end cap |46 into the guide slot |8|.Preferably, but not necessarily, suitable yielding means is provided tourge the disk in one of its guided directions. For this purpose I show asuitable helical spring |85 seated in a hollow screw |86.

Mounted in a tubular extension |81 in the end cap |48 of the oil pump isa suitable control shaft |88, on the inner end of which is aneccentrically positioned linger that extends into the previouslymentioned diametrical slot |18. It is apparent that rotation of thecontrol shaft |88 will vary the position of the finger |90 in itseccentric orbit, and will thereby vary the position of the eccentriccontrol |11 in the -flexible pocket formed by the four piston heads. Asheretofore indicated, the range of adjustment thus provided includes aconcentric position for the eccentric control |11.

The control shaft |88 is shown surrounded by suitable packing |9| thatis held in place by a suitable gland |92. 'I'he gland |92 may betightened down against the packing to create any desired degree offrictional resistance to rotation of the control shaft |88, and usuallysufflcient friction will be provided to maintain the control shaft inany position of adjustment in opposition to the force exerted by thespring |85. The outer end of the control shaft |88 is flattened asindicated in Fig. 2 so that the previously mentioned lever 58 may benon-rotatably mounted thereon.

One feature of the described construction is the manner in which thepiston heads are prevented from rotating about their own axes. Asindicated in Figs 2, 6 and 7, the flat face |12 of the web |68interconnecting the two piston heads |61 lies against the rounded sideof the web |1| and thereby prevents rotation of the two piston heads 13tion of the two piston heads |10 about their axis. 'I'hus the eccentriccontrol |11 not only serves its normal control purpose but also servesto prevent rotation of the four piston heads about their axes.

The operation of the oil pump may be readily understood from theforegoing description. It is readily apparent that the fuel oilcirculated by the pump is heated in the three stages exemplifieddiagrammatically in Fig. 4, as heretofore explained. Since during normaloperation the heat of compression generated vby the air pump 24 issubstantial, the burden placed on the heater 20 is much lighter thanwould ordinarily be required, and the heater 20 may be a relatively.

small coil. As a result the initial cost of the heater is lessened andthe amount of electric current consumed for preheating the fuel oil isreduced.

It will be noted that simply removing the screws |41 permits the oilpump to be dismounted from the air pump, and that such dismounting doesnot involve the usual necessity of disconnecting pipes in the fuel oilcirculation system. In this connection it will be noted that the rotorconstitutes in eiTect a second shaft which operates the oil pump and isconnected to the driving shaft 86 through the coupler |60. Suchdismounting oi' the oil pump not only makes the interior of the oil pumpaccessible for inspection, repair or servicing, but also exposes thebronze ring |25 for servicing or inspection of the sealing means aroundthe shaft 86 between the oil pump and the air pump.

Modified practice of the invention In a modified practice of theinvention the heater 20 is employed only temporarily at the beginning ofan operating period of the apparatus. the normal nreheatinn.r of thefuel oil over operating periods being by the heat of compressiongenerated in the air pump 24. cates the changes in the electrical systemof Fig. 1 that mav be made to carry out the contemplated modifiedpractice.

Much of the arrangement shown in Fig. is unchanged from that shown inFia'. 1. Thus a wire |95 from one side of the line 45 has a branch |96to the ignition transformer 49. and a second branch |61 to one side ofthe previously mentioned motor 22. Likewise the wire |95 is connected toone side of a heating element |98 in the relav 48 that serves to heatthe bi-metal element |99 therein. which bi-metal element controls aswitch 200 in the relay. In the same manner as before a wire 202connects the second side of the heating element |98 with one side of themain heater 29 for preheating the oil in the tube i9 leading to thenozzle I8.

The wiring diagram in Fig. 10 differs from the wiring diagram 5| inhaving the second side of the heater connected by a wire 203 with thewire 205 that returns from the ignition transformer 49 to the previouslymentioned relay 41. Thus the heater '20 is placed in parallel with theignition transformer 49. The diagram in Fig. 10 further differs in theaddition of a switch 206 in parallel switch 200, the switch 206 closingin response to rise in pressure in the air course that suppliesatomizing air to the burner nozzle. Fig. 10 shows a Sylphon 201 fromwhich a pipe 208 extends to the air supply system. The pipe 208 may beconnected, for example, to the previously mentioned air pipe 30 or tothe previously men- Fig. 10 inditioned air pipe 32, or may be connecteddirectly to the chamber I2 in the main housing.

'I'he operation of the modified system is as follows: When the roomthermostat or boiler control 46 calls for heat, Minneapolis-HoneywellE1-l7 relay 41 will be energized to close an electric p circuit to thedelayed action switch 48, thereby allowing current to iiow to the heater20, the ignition transformer 49, and the heating element |98 thataiiects'the temperature of the bi-metalelement |99. After a delay oftwenty-iive seconds, for example, the warping of the bi-metal element|99 against the switch 200 will close the switchv to energize the motor22 for starting the secondary air fan or blower 23, the primary oratomizing air pump 24, and the oil pump 25. Thus the heater '20 isenergized prior to energization of the oil pump and continues to beenergized after the.

oil pump is started.

The rising air pressure caused by operation of the air pump 24eventually causes the Sylphon 201 to close the switch 206, thusestablishing a second path for current iiow to the motor 22independently of the switch 200. A short time later the rise in thestack temperature causes the relay 41 to cut off the ignition circuit,and since the heater 20 is parallel with the ignition circuit the heater20 is also cut off, and will remain out oil, during the rest of thecombustion period.

Thus the heater 20 is energized for only a rela- -tively short initialperiod for starting the burner, and is automatically cut off as soon asthe heat of compression generated by the air pump 24 is suiiicient forthe normal required preheating of the oil.

This application is a continuation-in-part of my applications SerialNos. 428,390 and 428,391, filed January 27, 1942. for Linuid Fuel BurnerSvstem, and of my application Serial No. 428,392, filed on the samedate, for Liquid Fuel Burner which have matured. respectively. intoPatents Nos. 2,397,986. 2.397,987 and 2,397,988, all issued on April 9,1946.

The four copending applications mentioned herein are made a part of thepresent disclosure by reference.

My description in specific detail of the preferred practice of theinvention will suggest to those skilled in the art various changes andsubstitutions within the scope of the appended claims.

I claim as my invention:

1. In a dual pump, a iirst pump having a casing provided with a pumpchamber having inlet and outlet ports, a first shaft extending into saidpump chamber and having a pumping element associated therewith, saidshaft passing through a side wall of the casing, a second pump adaptedto be mounted on said side wall of the rst pump casing and having acasing provided with a pump chamber having inlet and outlet ports, asecond shaft extending into said second pump chamber and having apumping element associated therewith, said second shaft being insubstantial alignment with said first shaft, a detachable couplingdevice between said two shafts whereby the two shafts are rotated inunison and may be readily disconnected, said first pump casing beingprovided with fluid inlet and outlet passageways which are adapted 'tobe connected at one end by fluid connection means to a source of fluidfor the second pump and a point of use for lsuch fluid. respectively,and to communicate at their other ends with said inlet and outlet ports,respectively,

of the second pump when the two pumps are mounted in juxtaposedrelation, and readily detachable fastening means for securing the twopumps together, whereby the second pump may be removed intact from saidrst pump by merely removing said fastening means and without disturbingsaid fluid connection means.

2. The combination set forth in claim 1 which includes a seal around oneof said shafts to cut ofi communication between the two pumps along saidtwo shafts, said seal being at a position on said one shaft to beexposed by the removal of said second pump from the casing of the firstpump.

3. The combination set forth in claim 1 in which said fluid inlet andoutlet passageways are in heat-exchange relationship with the rst pumpchamber, whereby the fluid acted upon by the second pump is heated bythe heat of compression of the first pump both before and after saidiiuid passes through said second pump.

4. The combination as set forth in claim 1 in which said coupling deviceincludes a slot in the end of one of said shafts and a mating rib on theend of said other shaft.

` EARL JOSEPH SENNINGER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,135,414 Vincent Apr. 13, 19151,541,768 Diller et al. June 9, 1925 1,592,024 Jennings July 13, 19261,886,751 Schreiber Nov. 8, 1932 1,923,600 Warner Aug. 22, 10331,968,023 Bijur July 31, 1934 2,009,137 Kleckner July 23, 1935 2,199,454Andler et al May 7, 1940 2,397,986 Senninger Apr. 9, 1946 2,397,987Senninger Apr. 9, 1946 2,397,988 Senninger Apr. 9, 1946 2,409,477 DeLancey Oct. 15, 1946 2,411,509 Endebak Nov. 26, 1946

